The temperature regulation of refrigerated containers such as, for example, refrigerated truck bodies and trailers, is managed by providing a combination of cooling elements (such as refrigeration units and/or “cold plate” devices, for example) and insulated structural elements. The required cooling capacity of the cooling elements is largely dependent on the difference in temperature that must be maintained between the interior and exterior of the refrigerated container. Furthermore, the cost and complexity of the cooling system may be substantially reduced if the structure is thermally efficient (as quantified, for example, by a high “R” value). Thus, refrigerated containers are often constructed from components that serve both as structural components and insulating elements.
Conventional insulated structural elements utilized in refrigerated containers include a metal frame sandwiched between fiberglass layers. In order to provide insulation to the structure, foam is injected or blown into the space defined between the fiberglass layers. Such conventional insulated structures suffer from several technical deficiencies. First, the metal frame adds considerable weight to the assembly. The metal frame also creates significant heat transfer pathways or “thermal shorts” between the fiberglass layers that may degrade the overall R value of the structural element. In addition, conventional insulated structures also suffer from durability problems that cause the degradation of the structure's insulating capacity over time. For example, as conventional insulated structures are subjected to the everyday rigors of use and transport, the injected and/or blown foam layer tends to break apart, which may result in serious degradation of the R value of the structure.
Although conventional insulated structures suffer from the disadvantages outlined above, their use is still prevalent in refrigerated cargo and storage applications primarily due to availability, relative ease of assembly and low cost, and because the use of metal-reinforced fiberglass panels (having blown foam insulating filler) is relatively consistent and well-known. However, in light of the shortcomings of these conventional insulated structures, there exists a need in the art for an insulated structural element for use in refrigerated containers (such as, for example, refrigerated truck bodies and trailers) that is lightweight, durable, and provides a robust and thermally-efficient insulating capacity.